diff options
| author | Daniel Borkmann <daniel@iogearbox.net> | 2017-12-14 21:07:24 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2017-12-15 18:19:35 +0100 |
| commit | 87338c8e2cbb317b5f757e6172f94e2e3799cd20 (patch) | |
| tree | 5190b98815efc7a2c96a8a49c3b443ab9565fcc5 /arch/powerpc/net | |
| parent | bpf, s390x: do not reload skb pointers in non-skb context (diff) | |
| download | linux-87338c8e2cbb317b5f757e6172f94e2e3799cd20.tar.xz linux-87338c8e2cbb317b5f757e6172f94e2e3799cd20.zip | |
bpf, ppc64: do not reload skb pointers in non-skb context
The assumption of unconditionally reloading skb pointers on
BPF helper calls where bpf_helper_changes_pkt_data() holds
true is wrong. There can be different contexts where the helper
would enforce a reload such as in case of XDP. Here, we do
have a struct xdp_buff instead of struct sk_buff as context,
thus this will access garbage.
JITs only ever need to deal with cached skb pointer reload
when ld_abs/ind was seen, therefore guard the reload behind
SEEN_SKB.
Fixes: 156d0e290e96 ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Sandipan Das <sandipan@linux.vnet.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'arch/powerpc/net')
| -rw-r--r-- | arch/powerpc/net/bpf_jit_comp64.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 46d74e81aff1..d183b4801bdb 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -763,7 +763,8 @@ emit_clear: func = (u8 *) __bpf_call_base + imm; /* Save skb pointer if we need to re-cache skb data */ - if (bpf_helper_changes_pkt_data(func)) + if ((ctx->seen & SEEN_SKB) && + bpf_helper_changes_pkt_data(func)) PPC_BPF_STL(3, 1, bpf_jit_stack_local(ctx)); bpf_jit_emit_func_call(image, ctx, (u64)func); @@ -772,7 +773,8 @@ emit_clear: PPC_MR(b2p[BPF_REG_0], 3); /* refresh skb cache */ - if (bpf_helper_changes_pkt_data(func)) { + if ((ctx->seen & SEEN_SKB) && + bpf_helper_changes_pkt_data(func)) { /* reload skb pointer to r3 */ PPC_BPF_LL(3, 1, bpf_jit_stack_local(ctx)); bpf_jit_emit_skb_loads(image, ctx); |